//@HEADER
// ************************************************************************
//
//                        Kokkos v. 4.0
//       Copyright (2022) National Technology & Engineering
//               Solutions of Sandia, LLC (NTESS).
//
// Under the terms of Contract DE-NA0003525 with NTESS,
// the U.S. Government retains certain rights in this software.
//
// Part of Kokkos, under the Apache License v2.0 with LLVM Exceptions.
// See https://kokkos.org/LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//@HEADER

#ifndef KOKKOS_EXPERIMENTAL_IMPL_VIEW_CTOR_PROP_HPP
#define KOKKOS_EXPERIMENTAL_IMPL_VIEW_CTOR_PROP_HPP

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------

namespace Kokkos {
namespace Impl {

struct SequentialHostInit_t {};
struct WithoutInitializing_t {};
struct AllowPadding_t {};

// FIXME: AccessorArg_t needs to be templated
// This really needs to be templated on the argument type
// But that adds some more complication, preventing simply
// copying the code from the above properties.
// For Sacado we only need a size_t for fad_size
// We can template this later in a separate change.
struct AccessorArg_t {
  size_t value{};
};

template <typename>
struct is_view_ctor_property : public std::false_type {};

template <>
struct is_view_ctor_property<SequentialHostInit_t> : public std::true_type {};

template <>
struct is_view_ctor_property<WithoutInitializing_t> : public std::true_type {};

template <>
struct is_view_ctor_property<AllowPadding_t> : public std::true_type {};

template <>
struct is_view_ctor_property<AccessorArg_t> : public std::true_type {};

//----------------------------------------------------------------------------
/**\brief Whether a type can be used for a view label */

template <typename>
struct is_view_label : public std::false_type {};

template <>
struct is_view_label<std::string> : public std::true_type {};

template <unsigned N>
struct is_view_label<char[N]> : public std::true_type {};

template <unsigned N>
struct is_view_label<const char[N]> : public std::true_type {};

//----------------------------------------------------------------------------

template <typename... P>
struct ViewCtorProp;

// Forward declare
template <typename Specialize, typename T>
struct CommonViewAllocProp;

/* Dummy to allow for empty ViewCtorProp object
 */
template <>
struct ViewCtorProp<void> {};

/* Common value_type stored as ViewCtorProp
 */
template <typename Specialize, typename T>
struct ViewCtorProp<void, CommonViewAllocProp<Specialize, T>> {
  ViewCtorProp() = default;

  using type = CommonViewAllocProp<Specialize, T>;

  KOKKOS_FUNCTION
  ViewCtorProp(const type &arg) : value(arg) {}
  KOKKOS_FUNCTION
  ViewCtorProp(type &&arg) : value(arg) {}

  type value;
};

/* Property flags have constexpr value */
template <typename P>
struct ViewCtorProp<std::enable_if_t<std::is_same_v<P, AllowPadding_t> ||
                                     std::is_same_v<P, WithoutInitializing_t> ||
                                     std::is_same_v<P, SequentialHostInit_t>>,
                    P> {
  ViewCtorProp() = default;

  using type = P;

  ViewCtorProp(const type &) {}

  type value = type();
};

/* Map input label type to std::string */
template <typename Label>
struct ViewCtorProp<std::enable_if_t<is_view_label<Label>::value>, Label> {
  ViewCtorProp() = default;

  using type = std::string;

  ViewCtorProp(const type &arg) : value(arg) {}
  ViewCtorProp(type &&arg) : value(std::move(arg)) {}

  type value;
};

template <typename Space>
struct ViewCtorProp<std::enable_if_t<Kokkos::is_memory_space<Space>::value ||
                                     Kokkos::is_execution_space<Space>::value>,
                    Space> {
  ViewCtorProp() = default;

  using type = Space;

  ViewCtorProp(const type &arg) : value(arg) {}

  type value;
};

template <>
struct ViewCtorProp<void, AccessorArg_t> {
  ViewCtorProp() = default;

  using type = AccessorArg_t;

  KOKKOS_FUNCTION
  ViewCtorProp(const type arg) : value(arg) {}

  type value;
};

template <typename T>
struct ViewCtorProp<void, T *> {
  ViewCtorProp() = default;

  using type = T *;

  KOKKOS_FUNCTION
  ViewCtorProp(const type arg) : value(arg) {}

  type value;
};

// For some reason I don't understand I needed this specialization explicitly
// for NVCC/MSVC
template <typename T>
struct ViewCtorProp<T *> : public ViewCtorProp<void, T *> {
  static constexpr bool has_memory_space     = false;
  static constexpr bool has_execution_space  = false;
  static constexpr bool has_pointer          = true;
  static constexpr bool has_label            = false;
  static constexpr bool allow_padding        = false;
  static constexpr bool initialize           = true;
  static constexpr bool sequential_host_init = false;
  static constexpr bool has_accessor_arg     = false;

  using memory_space    = void;
  using execution_space = void;
  using pointer_type    = T *;

  KOKKOS_FUNCTION ViewCtorProp(const pointer_type arg)
      : ViewCtorProp<void, pointer_type>(arg) {}
};

// If we use `ViewCtorProp<Args...>` and `ViewCtorProp<void, Args>...` directly
// in the parameter lists and base class initializers, respectively, as far as
// we can tell MSVC 16.5.5+CUDA 10.2 thinks that `ViewCtorProp` refers to the
// current instantiation, not the template itself, and gets all kinds of
// confused. To work around this, we just use a couple of alias templates that
// amount to the same thing.
template <typename... Args>
using view_ctor_prop_args = ViewCtorProp<Args...>;

template <typename Arg>
using view_ctor_prop_base = ViewCtorProp<void, Arg>;

template <typename... P>
struct ViewCtorProp : public ViewCtorProp<void, P>... {
 private:
  using var_memory_space =
      Kokkos::Impl::has_condition<void, Kokkos::is_memory_space, P...>;

  using var_execution_space =
      Kokkos::Impl::has_condition<void, Kokkos::is_execution_space, P...>;

  struct VOIDDUMMY {};

  using var_pointer =
      Kokkos::Impl::has_condition<VOIDDUMMY, std::is_pointer, P...>;

 public:
  /* Flags for the common properties */
  static constexpr bool has_memory_space    = var_memory_space::value;
  static constexpr bool has_execution_space = var_execution_space::value;
  static constexpr bool has_pointer         = var_pointer::value;
  static constexpr bool has_label =
      Kokkos::Impl::has_type<std::string, P...>::value;
  static constexpr bool allow_padding =
      Kokkos::Impl::has_type<AllowPadding_t, P...>::value;
  static constexpr bool initialize =
      !Kokkos::Impl::has_type<WithoutInitializing_t, P...>::value;
  static constexpr bool sequential_host_init =
      Kokkos::Impl::has_type<SequentialHostInit_t, P...>::value;
  static constexpr bool has_accessor_arg =
      Kokkos::Impl::has_type<AccessorArg_t, P...>::value;
  static_assert(initialize || !sequential_host_init,
                "Incompatible WithoutInitializing and SequentialHostInit view "
                "alloc properties");

  using memory_space    = typename var_memory_space::type;
  using execution_space = typename var_execution_space::type;
  using pointer_type    = typename var_pointer::type;

  // Construct from a matching argument list.
  //
  // Note that if P is empty, this constructor is the default constructor.
  // On the other hand, if P is not empty, the constraint implies that
  // there is no default constructor.
  // NOLINTBEGIN(modernize-type-traits)
  template <typename... Args,
            typename = std::enable_if_t<std::conjunction_v<
                std::is_constructible<view_ctor_prop_base<P>, Args &&>...>>>
  // NOLINTEND(modernize-type-traits)
  ViewCtorProp(Args &&...args)
      : ViewCtorProp<void, P>(std::forward<Args>(args))... {}

  // If we use `ViewCtorProp<void, Args>...` here MSVC gets confused
  // error C3528: 'args': the number of elements in this pack expansion
  // does not match the number of elements in 'P'
  // Using the alias view_ctor_prop_base here as below fixes the issue.
  // Encountered with MSVC 17 and CUDA 12.6
  template <typename... Args>
  KOKKOS_FUNCTION ViewCtorProp(pointer_type arg0, Args const &...args)
      : view_ctor_prop_base<pointer_type>(arg0),
        view_ctor_prop_base<typename view_ctor_prop_base<Args>::type>(args)... {
  }

  /* Copy from a matching property subset */
  KOKKOS_FUNCTION ViewCtorProp(pointer_type arg0)
      : ViewCtorProp<void, pointer_type>(arg0) {}

  // If we use `ViewCtorProp<Args...>` and `ViewCtorProp<void, Args>...` here
  // directly, MSVC 16.5.5+CUDA 10.2 appears to think that `ViewCtorProp` refers
  // to the current instantiation, not the template itself, and gets all kinds
  // of confused. To work around this, we just use a couple of alias templates
  // that amount to the same thing.
  template <typename... Args>
  ViewCtorProp(view_ctor_prop_args<Args...> const &arg)
      : view_ctor_prop_base<Args>(
            static_cast<view_ctor_prop_base<Args> const &>(arg))... {
    // Suppress an unused argument warning that (at least at one point) would
    // show up if sizeof...(Args) == 0
    (void)arg;
  }
};

#if !defined(KOKKOS_COMPILER_MSVC) || !defined(KOKKOS_COMPILER_NVCC)
template <typename... P>
auto with_properties_if_unset(const ViewCtorProp<P...> &view_ctor_prop) {
  return view_ctor_prop;
}

template <typename... P, typename Property, typename... Properties>
auto with_properties_if_unset(const ViewCtorProp<P...> &view_ctor_prop,
                              [[maybe_unused]] const Property &property,
                              const Properties &...properties) {
  if constexpr ((is_execution_space<Property>::value &&
                 !ViewCtorProp<P...>::has_execution_space) ||
                (is_memory_space<Property>::value &&
                 !ViewCtorProp<P...>::has_memory_space) ||
                (is_view_label<Property>::value &&
                 !ViewCtorProp<P...>::has_label) ||
                (std::is_same_v<Property, AccessorArg_t> &&
                 !ViewCtorProp<P...>::has_accessor_arg) ||
                (std::is_same_v<Property, WithoutInitializing_t> &&
                 ViewCtorProp<P...>::initialize) ||
                (std::is_same_v<Property, SequentialHostInit_t> &&
                 !ViewCtorProp<P...>::sequential_host_init)) {
    using NewViewCtorProp = ViewCtorProp<P..., Property>;
    NewViewCtorProp new_view_ctor_prop(view_ctor_prop);
    static_cast<ViewCtorProp<void, Property> &>(new_view_ctor_prop).value =
        property;
    return with_properties_if_unset(new_view_ctor_prop, properties...);
  } else
    return with_properties_if_unset(view_ctor_prop, properties...);

// A workaround placed to prevent spurious "missing return statement at the
// end of non-void function" warnings from CUDA builds (issue #5470). Because
// KOKKOS_ENABLE_DEBUG_BOUNDS_CHECK removes [[noreturn]] attribute from
// cuda_abort(), an unreachable while(true); is placed as a fallback method
#if (defined(KOKKOS_COMPILER_NVCC) && (KOKKOS_COMPILER_NVCC < 1150))
  Kokkos::abort(
      "Prevents an incorrect warning: missing return statement at end of "
      "non-void function");
#ifdef KOKKOS_ENABLE_DEBUG_BOUNDS_CHECK
  while (true)
    ;
#endif
#endif
}
#else

template <class ViewCtorP, class... Properties>
struct WithPropertiesIfUnset;

template <class ViewCtorP>
struct WithPropertiesIfUnset<ViewCtorP> {
  static constexpr auto apply_prop(const ViewCtorP &view_ctor_prop) {
    return view_ctor_prop;
  }
};

template <class... P, class Property, class... Properties>
struct WithPropertiesIfUnset<ViewCtorProp<P...>, Property, Properties...> {
  static constexpr auto apply_prop(const ViewCtorProp<P...> &view_ctor_prop,
                                   const Property &prop,
                                   const Properties &...properties) {
    if constexpr ((is_execution_space<Property>::value &&
                   !ViewCtorProp<P...>::has_execution_space) ||
                  (is_memory_space<Property>::value &&
                   !ViewCtorProp<P...>::has_memory_space) ||
                  (is_view_label<Property>::value &&
                   !ViewCtorProp<P...>::has_label) ||
                  (std::is_same_v<Property, AccessorArg_t> &&
                   !ViewCtorProp<P...>::has_accessor_arg) ||
                  (std::is_same_v<Property, WithoutInitializing_t> &&
                   ViewCtorProp<P...>::initialize) ||
                  (std::is_same_v<Property, SequentialHostInit_t> &&
                   !ViewCtorProp<P...>::sequential_host_init)) {
      using NewViewCtorProp = ViewCtorProp<P..., Property>;
      NewViewCtorProp new_view_ctor_prop(view_ctor_prop);
      static_cast<ViewCtorProp<void, Property> &>(new_view_ctor_prop).value =
          prop;
      return WithPropertiesIfUnset<NewViewCtorProp, Properties...>::apply_prop(
          new_view_ctor_prop, properties...);
    } else
      return WithPropertiesIfUnset<ViewCtorProp<P...>,
                                   Properties...>::apply_prop(view_ctor_prop,
                                                              properties...);
  }
};

template <typename... P, class... Properties>
auto with_properties_if_unset(const ViewCtorProp<P...> &view_ctor_prop,
                              const Properties &...properties) {
  return WithPropertiesIfUnset<ViewCtorProp<P...>, Properties...>::apply_prop(
      view_ctor_prop, properties...);
}

#endif

struct ExecutionSpaceTag {};
struct MemorySpaceTag {};
struct LabelTag {};
struct PointerTag {};
struct AccessorArgTag {};

template <typename Tag, typename... P>
KOKKOS_FUNCTION const auto &get_property(
    const ViewCtorProp<P...> &view_ctor_prop) {
  if constexpr (std::is_same_v<Tag, ExecutionSpaceTag>) {
    static_assert(ViewCtorProp<P...>::has_execution_space);
    using execution_space_type = typename ViewCtorProp<P...>::execution_space;
    return static_cast<const ViewCtorProp<void, execution_space_type> &>(
               view_ctor_prop)
        .value;
  } else if constexpr (std::is_same_v<Tag, MemorySpaceTag>) {
    static_assert(ViewCtorProp<P...>::has_memory_space);
    using memory_space_type = typename ViewCtorProp<P...>::memory_space;
    return static_cast<const ViewCtorProp<void, memory_space_type> &>(
               view_ctor_prop)
        .value;
  } else if constexpr (std::is_same_v<Tag, LabelTag>) {
    static_assert(ViewCtorProp<P...>::has_label);
    return static_cast<const ViewCtorProp<void, std::string> &>(view_ctor_prop)
        .value;
  } else if constexpr (std::is_same_v<Tag, PointerTag>) {
    static_assert(ViewCtorProp<P...>::has_pointer);
    using pointer_type = typename ViewCtorProp<P...>::pointer_type;
    return static_cast<const ViewCtorProp<void, pointer_type> &>(view_ctor_prop)
        .value;
  } else if constexpr (std::is_same_v<Tag, AccessorArgTag>) {
    static_assert(ViewCtorProp<P...>::has_accessor_arg);
    return static_cast<const ViewCtorProp<void, AccessorArg_t> &>(
               view_ctor_prop)
        .value;
  } else {
    static_assert(std::is_same_v<Tag, void>, "Invalid property tag!");
    return view_ctor_prop;
  }

// A workaround placed to prevent spurious "missing return statement at the
// end of non-void function" warnings from CUDA builds (issue #5470). Because
// KOKKOS_ENABLE_DEBUG_BOUNDS_CHECK removes [[noreturn]] attribute from
// cuda_abort(), an unreachable while(true); is placed as a fallback method
#if (defined(KOKKOS_COMPILER_NVCC) && (KOKKOS_COMPILER_NVCC < 1150))
  Kokkos::abort(
      "Prevents an incorrect warning: missing return statement at end of "
      "non-void function");
#ifdef KOKKOS_ENABLE_DEBUG_BOUNDS_CHECK
  while (true)
    ;
#endif
#endif
}
#if defined(KOKKOS_COMPILER_NVCC) && (KOKKOS_COMPILER_NVCC < 1150)
// pragma pop is getting a warning from the underlying GCC
// for unknown pragma if -pedantic is used
#ifdef __CUDA_ARCH__
#pragma pop
#endif
#endif
#ifdef KOKKOS_IMPL_INTEL_BOGUS_MISSING_RETURN_STATEMENT_AT_END_OF_NON_VOID_FUNCTION
#pragma warning(pop)
#undef KOKKOS_IMPL_INTEL_BOGUS_MISSING_RETURN_STATEMENT_AT_END_OF_NON_VOID_FUNCTION
#endif

template <typename Tag, typename... P>
KOKKOS_FUNCTION auto &get_property(ViewCtorProp<P...> &view_ctor_prop) {
  // Avoid code duplication by deferring to the const-qualified overload and
  // casting the const away from the return type
  const auto &tmp = get_property<Tag>(
      static_cast<const ViewCtorProp<P...> &>(view_ctor_prop));
  return const_cast<std::decay_t<decltype(tmp)> &>(tmp);
}

} /* namespace Impl */
} /* namespace Kokkos */

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------

namespace Kokkos {

namespace Impl {
struct ViewAllocateWithoutInitializingBackwardCompat {};

template <>
struct ViewCtorProp<void, ViewAllocateWithoutInitializingBackwardCompat> {};

// NOTE This specialization is meant to be used as the
// ViewAllocateWithoutInitializing alias below. All it does is add a
// constructor that takes the label as single argument.
template <>
struct ViewCtorProp<WithoutInitializing_t, std::string,
                    ViewAllocateWithoutInitializingBackwardCompat>
    : ViewCtorProp<WithoutInitializing_t, std::string>,
      ViewCtorProp<void, ViewAllocateWithoutInitializingBackwardCompat> {
  ViewCtorProp(std::string label)
      : ViewCtorProp<WithoutInitializing_t, std::string>(
            WithoutInitializing_t(), std::move(label)) {}
};
} /* namespace Impl */

using ViewAllocateWithoutInitializing =
    Impl::ViewCtorProp<Impl::WithoutInitializing_t, std::string,
                       Impl::ViewAllocateWithoutInitializingBackwardCompat>;

inline constexpr Kokkos::Impl::SequentialHostInit_t SequentialHostInit{};

inline constexpr Kokkos::Impl::WithoutInitializing_t WithoutInitializing{};

inline constexpr Kokkos::Impl::AllowPadding_t AllowPadding{};

/** \brief  Create View allocation parameter bundle from argument list.
 *
 *  Valid argument list members are:
 *    1) label as a "string" or std::string
 *    2) memory space instance of the View::memory_space type
 *    3) execution space instance compatible with the View::memory_space
 *    4) Kokkos::WithoutInitializing to bypass initialization
 *    4) Kokkos::AllowPadding to allow allocation to pad dimensions for memory
 * alignment
 */
template <class... Args>
auto view_alloc(Args &&...args) {
  using return_type = Impl::ViewCtorProp<typename Impl::ViewCtorProp<
      void, Kokkos::Impl::remove_cvref_t<Args>>::type...>;

  static_assert(!return_type::has_pointer,
                "Cannot give pointer-to-memory for view allocation");

  return return_type(std::forward<Args>(args)...);
}

template <class... Args>
KOKKOS_INLINE_FUNCTION
    Impl::ViewCtorProp<typename Impl::ViewCtorProp<void, Args>::type...>
    view_wrap(Args const &...args) {
  using return_type =
      Impl::ViewCtorProp<typename Impl::ViewCtorProp<void, Args>::type...>;

  static_assert(!return_type::has_memory_space &&
                    !return_type::has_execution_space &&
                    !return_type::has_label && return_type::has_pointer,
                "Must only give pointer-to-memory for view wrapping");

  return return_type(args...);
}

} /* namespace Kokkos */

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------

#endif
